Relay



April 30, 1957 G. o. WAGNER v 2,790,876

RELAY Filed March 22, 1954 2 sheets-Sheet 1 GEOQGE 0. KIWA/EQ,

INVENTOR.

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April 30, 1957 G. o. WAGNER 2,790,876

' RELAY Filed March 22, 19.54 l 2 She'ets-Sheet 2 IN VEN TOR. ,Q 650,@@E 0. M26/vae rraeA/Ey United States Patent O RELAY George O. Wagner,Burbank, Calif., assignor, by mesne assignments, to Elgin InstrumentCompany, Elgin, Ill., a corporation of Illinois Application March 22,1954, Serial No. 417,715

Claims. (Cl. 200-104) This invention relates generally to switches, landis particularly concerned with remotely controlled relays by rmeans 'ofwhich electrical circuits may be opened and closed through poweractuated devices such as solenoid energized from a remote point.

In an increasingly large eld of application, as particullarlyexemplified in aviation, there is a demand for small, light, andshock-proof relays having incorporated therein power means forfaithfully responsive, positive actuation, un'der the control of anoperator located at a remote control station.

In the design and construction of relays of this type it is veryimportant that dimensions and weight be restricted without sacrifice lofeffectiveness and durability and without undue increase in costs. Of noless importance is the stability of such device when subjected tovibration and shock. The incorporation of positively responsiveactuation and unyielding retention of parts both in their operated andrestored positions is also essential to successful relays in this iel'd.It is further required that strong and uniformly responsive power meansbe included to insure such positive actuation to operated position andunyielding retention in restored position. The compact unification ofthe parts of these relays within sealed containers is lalso desirable.

With these and similar problems in view, it is among the general objectsof the invention to provide a novel, effective, and eicient device ofthe character set forth, particularly Idesigned Ito meet theincreasingly rigid requirements of Air Force speciiications.

More specifically, it is among the objects of the invention to providean improved electromagnetic relay of miniature size but incorporatingtherein features of strength, durability, power actuation and faithfulperformance heretofore generally found only in relays of moresubstantial size.

A further obj-ect is to provide a compact relay of low weight withoutsacrifice of reliability and durability.

It is also an 'object of the invention to provide a relay that isvibration resistant and shock resistant, even though of light weight andsmall size.

The invention also includes las an object the provision of a compact andlight relay guarded from ambient conditions by hermetic sealing within arigid magnetic housing that forms part of the flux path of the actuatingsolenoid.

It is also an object of the invention to provide a powerful andmechanically eiiicient actuating means for a relay of the type underconsideration and to achieve this objective with economy of space andweight.

In addition to the other objects hereinabove specically enumerated, aswell as those which will be recognized from a consideration of thefollowing specification taken in conjunction with the accompanyingdrawings, lare those relating to structural details insuring uniformoperationl under adverse conditions of shock and vibration, longevity'of service without repair or adjustment, and economy of bothmanufacture and opera-tion.

The invention possesses numerous other iobjects and features ofadvantage, some of which, together with the foregoing, will be set forthin the following description of a relay that embodies the invention.Though only one form of relay constructed in accordance with theprinciples of this invention is described below and illustrated in theaccompanying drawing, it is to be understood that the invention is notlimited to the details of construction of this form of relay but thatthe invention may be embodied in other forms that fall within the scopeof the appended claims.

In the drawings wherein like reference characters indicate like elementsthroughout the several views:

Fig. 1 is a side elevational View of a relay embodying the features ofthis invention;

Fig. 2 is an enlarged vertical sectional view through the relay shown inFig. 1;

Fig. 3 is a transverse sectional view, with some parts broken away,taken on the line 3 3 of Fig. 2 looking in the direction of the arrowsthereof;

Fig. 4 is an exploded perspective view of one set of the contacts of therelay;

Fig. 5 is a detailed vertical section through the contact .actuator ofthe device;

Fig. 6 is a transverse section through the contact actuator, taken inline 6 6 of Fig. 5, looking in the direction of the farrows thereof;

Fig. 7 is an exploded view showing the contact actuator and its guidepins, and,

Fig. 8 is a schematic Wiring diagram of the relay as viewed from thetop.

In general terms, the embodiment of the invention here presented ischaracterized by a novel arrangement of a rigid member supporti-ng bothfixed contacts and movable contacts, actuating means for moving thelatter relatively to the former, power means for controlling theactuating means, `and an enclosing housing. More specifically, this formof the invention comprises 1a base mounting a circular multi-fold seriesof contact sets, each set including a pair of juxtaposed fixed contactson an interposed movable contact. The contacts are located at the innerends of contact terminals that extend through the base. A longitudinallyreciprooable, spring urged actuator is disposed centrally of thecircular series. The actuator includes peripheral, longitudinallyinclined actuating slots equal in number to the movable contacts.

A longitudinally movable actuator pin is carried by each of the moviablecontacts. Each of these pins engages a corresponding slot of theactuator. Thus, upon longitudinal reciprocation :of the actuator, aturning moment is applied to each movable contact arm to move itscontact from one to the other of its companion fixed contacts.Controlled reciprocation of the 'actuator against the force of thespring is provided by an integrally included, remotely controlled powermeans. In the form of the relay described herein, the power means is -asolenoid and an armature which constitutes an "operating shaft for theactuator. While the invention is not limited thereto, it contemplatesthe use of 1an enclosing housing that is `composed of magnetic material,thus forming a return path for the magnetic flux of the solenoid coil aswell as a seal for the internal parts.

Referring now more particularly to the drawings, the structu-recomprises an insulating base 10, preferably circular in form andconveniently manufactured of glass, Ithermo-setting plastic or somesimilar non-conducting or dielectric material. The base 10 is mountedwithin and is supported and protected by a peripheral metallic base ring11. The ring 11 extends upwardly `beyond the upper inner surface of thebase 10, its outer surface being rabbeted as at 12. to receive the loweredge of the enclosing housing 80. The inner surface yof the upward' 3extension of ring 11 is counter-bored as at .13 yto receive the lowerend of the linger `of a spacer and spring retaining-spider Si). Thisconstruction thus provides an intermediate upwardly extending `flange 14between the rabbet 12 and the counter-bore 13.

Extending through and moulded in the `base are two concentric circularseries of termin-al connectors, preferably formed `of tinned chromesteel wire. The outer circular series is composed of equally spacedpairs of right and left hand `fixed-contact terminals 15 and 16,respectively. In the `simplest design the .spacing between thefixed-contact terminal of one pair and the next adjacent lixed-contactterminal of lanother pair yis equal to the spacing between the terminalsof each Apair and thus a uniform circular spacing between `thesuccessive contacts 15 and 16 results. As shown here, six pairs, eachcomprising a right and left hand fixed-contact terminal, are provided,and thus the pairs, being `uniformly spaced, are disposed `on `eitherside of intermediate .609 divergent radii.

The inner concentric circular series of terminals comprises sixuniformly spaced movable Contact terminals 17 disposed in the plane ofthe intermediate 60 divergent radii referred to above and `are thus eachangularlyintermediate a corresponding pair of the yfixed contactterminals and are inwardly `spaced therefrom. Two additionaldiametrically opposite coil terminals 18 are 4also included in the innerconcentric circular series `as shown in Fig, A8. Terminals 18 arepreferably located equidistantly intermediate opposed pairs of movablecontact terminals, thereby uniformly 'balancing the circular dispositionof the inner circular series of movable contact terminals. Thus, `the`entire arrangement possesses la twofold symmetry about the coilterminals and the sets of contacts themselves possess a six-foldsymmetry.

The outer ends of all the terminals `are illustrated as formed withJ-shaped extremities 19 for convenience in making electrical connectionsto associated circuits. Such outer ends of the inner circular seriespreferably extend `beyond those of the outer circular series to furtherfacilitate making such connections. The inner ends 15', 16', `and 17 ofall` Contact terminals are straight and extend beyond the inner surfaceof the base 10 to provide mounting portions for the conta-ct arms, whilelike straight extensions 18 of the coil Iterminals 18 provide forv,electrical connection with coil leads.

inwardly protruding from the base 10, there is also provided a pair ofdiametrically opposite straight actuator guide pins 21. The inwardextension of guide pins 21 exceeds that of the inward extension of theinner ends 15', 16', 17 and 13 of the terminals. lPins 21 are arrangedat equal radial distances from the center `of `base 140 but within thecircle of the inner series of terminals thereby constituting an innerseparate and distinct two-pin series.

Mounted on the inner ends 15 and 16 yof the outer circular series ofright and left hand fixed-contact terminals 15 and 16 are a circular`series of corresponding opposed right and left hand xed contacts 22 and23. Each iixed contact comprises a relatively stiff blade, preferably ofPhosphor bronze and formed at its lower `end with a cylindrical sleeve24. Sleeves 24 receive the ends 15 and 16' of the iixed contactterminals Aand are secured vthereto adjacent the `inner surface of `base10 by welding or other suitable means. The upper opposite end of each`Contact is apertured as at 25 and receives through such aperture thestud end 26 of a headed, at faced, silver Icontact button 27. .lt will,of course, be understood that the contact buttons 27 of each pair faceinwardly in confronting relation to form oppositely disposed right andleft hand fixed Contact faces.

For alternative selective closure of the right rand left hand fixedcontacts, there is provided a circular series of movable contacts 30.Each movable contact 'blade 30' is formed with a cylindricalpin-encompassing sleeve 31 .similar to sleeves 24 of the blades 22 and23 for similar rigid attachment, as by welding, to the inwardlyextending ends 17 of the movable contact terminals 17. The oppositeupper or outer ends of the contacts 30 include wings 32. that extendradially outward of the blades 31 and thus between the contact `buttons27 of the blades 22 and 23. Each wing 32 is apertured to -receivetherethrough the shank of a silver contact button formed with right andleft hand conical contact heads 33 and 34, respectively.

The blades 3d upon which the movable contacts are -mounted are oflighter gauge material than the blades 22 and 23 in order to render suchblades more llexible and also to provide differences in the `freeperiods of oscillation of the fixed and movable blades. |By employingcooperating contact arms having different periods of oscillation, thedanger of excessive contact bounce, or chatter, is minimized whencontact is established either upon actuation to operated condition ordeactuation to restored condition.

Movement of the movable Contact members 30 'by which they are exed fromthe normal straight plane of Ithe blade, with little torsion, isimparted thereto by actuator pins 3S. Each pin 35 includes a straighthalf- Vround blade engaging end 36, the flat face of which is welded toone face of the blade at approximately the longitudinal center of theblade. The pins 35 extend `radially inward from the blades in the samenormal plane for a short distance and then turn to form a downwardlyextending and inclined slot follower 4bight 37 terminating in a returnbent terminal end 33. The pins 35 are more rigid than the at blades 30`and hence lateral motion imparted to the slot follower bights 37 laretranslated by bodily movement of the pins lto produce transverse flexingof the blades. Such flexing results in making and breaking Contactbetween right and left hand Contact heads 33 and 34 and right and lefthand fixed contact buttons 27.

Lateral motion of the pins 35 is produced by reciprocating movement of acircular cylindrical centrally disposed actuator composed of nylon orother suitable insulating material. The actuator 40 is slidably mountedupon the guide pins 21 received within spaced apertures 41 of theactuator so that rotation of the actuator within the structure isprecluded, while free longitudinal reciprocation on the pins ispermitted. Extending inwardly of the side walls of the actuator 4i) aresix inclined slots 42, each of which receives one of the follower4bights 37 of one actuating pin 3.3'. The slots 42 and bights 37 are ofSimilar inclination and beth may be either straight or helical. Sincethe pins 35 and their slot-follower bights 37 are iixed againstlongitudinal motion, it will be readily understood that longitudinalmotion of the actuator relative to the base, cams the pins laterally toflex the blades 30 transversely for movement of their Contact heads 33and 34 to and from engagement with the right and left hand fixed-contactheads 27 respectively.

As here shown, the normal or restored position of the actuator is adownward position. closely adjacent the base 10 and with the followerbights 37 toward the upper ends of the slots 42. ln this position, eachof the movable contacts 17 is `closed with one of the stationarycontacts 15, lbut contacts 17 and 'i6 are open.

Positive closure of contacts 1S and 17 and positive opening of thecontacts 17 and 16 are maintained while the relay is in the restoredposition, even in the presence of shock or vibration by a strong spiralcompression coil spring 44, preferably formed of heavy music wire. Thesmaller end terminal turn 45 of the spring 44 exerts downward pressureon the actuator 4l) through the medium of intermediate shim rings 46which may be readily added or removed to adjust the force applied by thespring. The opposite upper and larger terminal turn 47 of the spring 44is secured 'by clips 48 struck out from the body of a magnetic steelspacer plate 50, the central afferrare aperture 49 of which isconcentric with the actuator 40. Spaced depending arms 51 extend fromthe outer peripheral edge of the plate 50 toward the Vbase ring 11 whereinwardly turned ends 52 engage within the counterbore 13 and abut thebase 10. By this construction it will -be seen that the spring isconfined in operative pressure relation, suitably adjusted by shims 46,with the actuator to bias the actuator towards the restored positionshown. The peripheral edges of plate are also provided withdiametrically opposite recesses 53 and 54 through which the coil leadsmay pass to the ends 20 of the solenoid.

Power actuation of the actuator to an upward, operated position is, inthis form of the invention, provided :by electromechanical meanscomprising a magnetic steel plunger operating within a stationary brasscoil sleeve 61 fitted within the central cylinder 62 of a molded nyloncoil bobbin. The lower end 63 of the solenoid plunger 60 may be serratedas shown in Fig. 5 and pressed within the central receiving bore 64 ofthe actuator to provide .a positive rigid connection between actuatorand plunger.

The opposite upper end 60a of the plunger 60 is conical, .thus adaptingit to be received within `and guided 'by :the conforming conical walls65 of a stationary, electrical .steel core member 66. As will be noted,an air gap 67 Eis formed between conical plunger end 64 and conical=core walls 65. The air gap 67 constitutes a dash-pot which cushions themovement of the plunger and actuator Awhen the solenoid becomesenergized or deenergiz-ed.

The nylon coil bobbin is formed with top and bottom end-flanges 70 and71 respectively formed integral with the ends of the central cylinder62. The coil 72 is prefer- :ably loosely wound about the cylinder 62within the confines of the end flanges 76 and 71 with a minimum ofstretch, and the outer surface of the coil is inwardly spaced from theperipheral edges of the anges 70 and 71, to accommodate expansion athigh temperatures. The lower flange 71 is formed at one peripheral edgewith a tapped boss 73 to receive therethrough the terminal end of theouter coil winding. A companion tapped boss 74 is located diametricallyopposite the boss 73 and each is provided with grooves 75 to receive theedges of the recesses 53 of plate 50. The companion boss 74 communicateswith a radial groove 76 in the inner face of the ange `and in which theterminal end lof the inner coil winding is laid.

The relay construction is completed by the provision of a lmagneticsteel housing shell 80 of cylindrical cupshaped design. The lower openend 81 of the housing S0 is preferably rigidly, permanently, andhermetically sealed, as by welding, to the steel 'base ring 11, beingSeated Within the ra-bbet 12 of the latter. The side walls of the steelhousing extend downwardly and around the spacer plate 50 and around thecoil 72 and in snug engagement with the peripheral edges of flanges 70and 71. The closed outer end S2 of the housing bears against the outerface of upper flange 70 and is centrally apertured as at 83 to receivetherethrough the shank 84 of the outer end of steel c-ore member 66.Externally of the end 82, the shank S4 is headed over as at 85 torigidly secure the housing and core member together and in ux conductingrelationship. For mounting the relay in desired location, aperturedanges 86 may be welded on opposite sides of the housing, as shown.

The operation of the device, being quite simple, is believed to be clearfrom the forgoing discussion of the structure, arrangement, and functionof the parts. Suflce it therefore to say that as and when the coil isenergized, the solenoid lifts the actuator which is constrained by theactuator pins to move in a longitudinal direction, forcing the followerbights to move laterally to an extent depending on the inclination ofthe actuator slots and such movement imparts bending motion to themovable contacts to force them to break contact with one correspondingstationary contact and to make contact with the other correspondingcontact. Since the magnetic force produced by the coil is more thansuicient to overcome the spring force, insufficient movement of theactuator when current is applied is precluded. Conversely, when the coilis ide-energized the movable contacts are flexed in the oppositedirection forcing them to break with the corresponding latter contactand to make with the corresponding former contact, The spring isrelatively powerful compared to the work required to return the parts totheir restored position so that upon de-energization of the coil aprompt and permanent return of the contacts to their restored positionis insured.

Thus, provision is made for positive closure of each movable contact 17with a corresponding stationary contact 16 and positive opening of thecontacts 17 and 15 in the operated position by employing a solenoid thatexerts a large force compared with that of the spring. Thus, positivereliable action is attained in the relay, both when actuated tooperative position and when deactuated to restored position.

From the foregoing, it will be seen that the invention provides arugged, durable, compact and hermetically sealed relay. The parts are sodesigned, assembled, in terrelated and secured as to provide shockresistance and to withstand excessive vibration for long periods.

One important feature of' the invention resides inthe use of the steelprotective housing as a path of low magnetic reluctance. This featureprovides an arrangement in which weight is restricted while stillproviding eicient operation of the solenoid with a minimum supply ofelectrical energy.

Though only one embodiment of the invention has been described herein indetail, it will be understood that Various changes which will nowsuggest themselves to those skilled in the art may be made in thematerial, form, details of construction, and arrangement of the elementsand number of contacts of the relay without departing from the conceptsof the invention. It will be noted, for example, that relays embodyingsome of the concepts of my invention may be constructed which employother power actuating means than those specifically disclosed herein.Reference is therefore made to the appended claims for a definition ofthe limits of the invention.

I claim:

1. In a relay, a base, a first and second circular series of stationarycontacts mounted on said base, a concentric` third circular series ofcooperating contacts mounted on said base and normally making contactsrespectively with the first series of said contacts, said third series-being laterally movable spring contacts, an actuator mounted forreciprocating movement along the axis of said circular series, andmotion translating means between said actuator and said third movablecontacts for laterally moving said third movable contacts from said rstseries to said second series of contacts in response to reciprocation ofsaid actuator, said motion translating means including a slotted drumconnected to said actuator, the slots in said drum being angularlydisposed relative to said movable contacts, and means including rigidactuator pins connected to said third series of contacts, `and slidinglydriven by said slots to effect the lateral movement of said first andsecond series of contacts.

2. In a relay, a base, a circular series of stationary contacts mountedon said base, a concentric circular series of cooperating laterallyfiexible contacts mounted on said base, an actuator having inclinedperipheral slots mounted for reciprocation along the axis of saidseries, and motion translating pin means engaging the slots of saidactuator, said pin means directly engaging saidv of stationary contactsrigidly mounted on said base, a. third circular-series-of4cooperatinglaterally flexible contacts rigidly mounted `on said `base,an actuatorhaving axially extending inclined surface slots mounted foraxial reciprocation within said series and along the axis thereof, andslotfollowers rigidly secured tosaid flexible contacts and slidablewithin said slots, laterally flexing said laterally `flexible contactsin response to reciprocation of said actuator.

4. In a relay, a rigid circular base, a circular series of stationarycontacts having right and left hand pairs of contact` surfaces rigidly:mounted on said base, a concentric radially spaced circular series ofcooperating laterally flexiblecontacts rigidly mounted onsaid basehaving movable contact surfaces disposed between the right and left handpairs of stationary y contact surfaces, an actuator' mounted forreciprocating movement within said circular seriesand along theaxisthereof and having longitudinally extending inclined cam slotsformed-therein, and motion translating means comprising rigid pinscarried by .isaid flexible contacts rigidly secured to said movablecontact surfaces and slot followers mounted within said slots forlaterallyilexing'said flexible contacts from cont-act with one ofsaidpairs to contact with the other of said pairs in `response toreciprocation of said actuator.

5. Ina relay, a rigid, circular base, a circular series of stationarycontacts having right and left hand pairs of contact surfaces rigidlymounted on said base, a concentric radially spaced circular series ofcooperating laterally flexible `contacts rigidly mounted on said basehaving movable contact surfaces disposed between the right and left handpairs of stationary contact surfaceaan actu ator mounted forreciprocating movement within said circular series and along the axisthereof, longitudinally extending inclined cam slots in 'said actuator,motion translating means comprising rigid pins rigidly secured to saidflexible ,contacts and slot fol-lowers mounted within said slots forlaterally flexing'said flexible contacts from contact with one of saidpairs to contact with the other of said pairs in response toreciprocation of said actuator, a solenoid plunger coaxially mounted onsaid actuator, an'd a solenoid coil coaxially surrounding said plungerto reciprocate said actuator upon energization thereof..

6. In a relay, a rigid circular base, a circular series `of stationarycontacts having right and left hand pairs `of contact surfaces rigidlymounted on said base, a concentric radially spaced circular lseries ofcooperating laterally flexible contacts rigidly mounted on said basehaving movable Contact surfaces disposed between the right and left handpairs of stationary contact surfaces, a contact actuator mounted forreciprocating movement within said circular series and along 'the ax'sthereof, longitudinally extending inclined cam slots in said actuator,rigid motion translating pins rigidly secured to said flexible contactsincluding followers mounted within said slots vfor lateral movement inre spouse to reciprocation of said actuator, a coil spring eugaging saidactuator to bias the same in one direction, a solenoid plunger carriedby said actuator, and a solenoid coil surrounding said plunger' operableupon energization thereof to move Said actuator in the oppositedirection against'the force of said coil spring.

7. In adevicc of the character described, a base, a circular series ofright and left hand stationary Contact connectors extending through saidbase, an inner circular series of movable Contact connectors extendingthrough base, a pair of guide pins extending inwardly of 'said basewithin the inner circular series of movable contact connectors, rightand left han-d stationary contacts mounted `on Said stationary Contactconnectors, laterally flexible movable contact members mounted ou saidmovable contact connectors, a cylindrical actuator having inclinedsurface slots mounted on said pins for reciprocation with respectthereto, rigid actuator pins carried by said movable contact members,slot follower bights formed in said actuator pins `and fitted Withinsaid slots, a solenoid plunger Llll tid

on said actuator, a solenoid coilsurrounding said plunger, anda magnetic`casinghermetically sealed with said `,base and enclosing said contacts,actuator, plunger and coil.

8. ln a devicecf the character described, a base, a circular series ofright and left hand stationary. contact connectors extending throughsaid base each including an inner straight stationary contact mountingportion, an inner circular series of iovable contact connectorsextending through said base each including an inner straight movablecontact mounting portion, a pair of gu'idepins extending inwardly ofsaid base within the inner circular series of movable contactconnectors, right and left hand stationary contacts mounted on saidstationary contact mounting portions, laterally lflexible movablecontact members mounted on said movable `contact mounting portions,pairs of right and left hand juxtaposed `contact surfaces carried bysaid vright and left hand stationary contacts, movable contact surfacesinterposed between said right and left hand contact surfaces `carried bysaid laterally flexible movable contact members, a cylindrical actuatorhaving inclined surface slots mounted on said pins `for reciprocationwith respect thereto, rigid actuator pins carried by said movablecontact members, slot follower bights formed in said actuator pins andfitted within said slots, a solenoid plunger on said actuator, asolenoid coil surrounding said plunger, and a magnetic casinghermetically sealed with said base and enclosing said contacts,actuator, plunger and coil.

9. ln a device of the character' described, a base, a circular'series`of right andleft hand stationary contact connectors extending throughsaid base each including an inner straight stationary contact mountingportion, an inner circular series of movable contact connectorsextending through said base, each including an inner straight movablecontact mounting portion, a pair of guide pins extending inwardly ofsaid base within the inner circular series of movable contactconnectors, right and left hand stationary contacts mounted on saidstationary Contact mounting portions, laterally exible movable Contactmembers mounted on said movable contact mounting portions, pairs ofright and left hand juxtaposed contact surfaces carried by said rightand left hand stationary contacts, movable contact surfaces interposedbetween said right and left hand contact surfaces carried by saidlaterally flexible movable contact members, a cylindrical actuatorhaving inclined surface slots mounted on said pins for reciprocationwithrespect thereto, sprin g means for urging said actuator towards saidbase, means for adjusting the tension of said spring means, rigidactuator vpins carried by said movable contact members, Slot followerbghts formed in said actuator pins and fitted within said slots, asolenoid plunger on said actuator, a solenoid coil surrounding saidplunger, and a magnetic casing hermetically scaled with said base andenclosing said contacts, actuator, plunger and coil.

l0. In a device of the character described, a circular dielectric base,a circultr series of right and left hand stationary contact connectorsextending through said base each including an outenreturn bent conductorreceiving portion and an inner straight stationary contact mountingportion, an inner circular series of movable contact connectorsextending through said base each including an outer return bentconductor receiving portion and an inner straight movable contactmounting portion, a pair of coil terminal connectors extending throughsaid base, each having outer return bent conductor receiving .portionsand inner straight coil terminal receiving portions, a pair ofrguidcpins extending inwardly of said base withiu the inner circular series ofmovable contact connectors, right and left hand stationary contactsmounted on said stationary Contact mounting portions, laterally flexiblemovable contact members mounted on said movable contact mountingportions, pairs of right and left hand juxtaposed Contact surfacescarried by said right and left hand stationary contacts, movable contactsurfaces interposed between said right and left hand contact surfacescarried by said movable laterally exible movable contact members, acylindrical actuator having inclined surface slots mounted on said pinsfor reciprocation with respect thereto, spring means for urging saidactuator towards said base, means for adjusting the tension of saidspring means, rigid actuator pins carried by said movable contactmembers, slot follower bights formed in said actuator pins and iittedwithin said slots, a solenoid plunger on said actuator, a solenoid coilsurrounding said plunger, and a magnetic casing hermetically sealed withsaid base and enclosing said contacts, actuator, plunger and coil.

References Cited in the le of this patent UNITED STATES PATENTS

